Exhibit Antiques has dated this piece to the Georgian era.
A fine Regency glass decanter dating to c1815. It has its original diamond cut stopper.
Flutes cuts around the base which has been star cut.

You can an example of this decanter on page 248 of "The Decanter, An Illustrated History Of Glass from 1650" by Andy McConnell
Date & Origin
England, c1815
Condition
Excellent, no chips cracks or restoration, grazing to cut edges of stopper and decanter, very minor residue at the base of the decanter.
Dimensions
Height: 27.5cm (including stopper) Diameter: 11cm
Exhibit Antiques has dated this piece to the Georgian era.
Specialists in 18th & 19th century antique glass
You can view the stock and full dealer information on the Exhibit Antiques Profile Page